steve_333

I've had my Civic for almost a year now and I've constantly hit 10-11L/100km (25-27mpg) on one tank of gas while mostly driving in mixed highway and street conditions during summer and winter.

This mileage seems pretty low for a car with a 1.7L engine and I'm wondering if anyone else has had a similar problem?

The car idles very smoothly at around 300-400rpm and otherwise runs very well.

Thanks!

Colin42

idle seems a little low, are you driving it like a race car? (dont do that)
check your plugs, air filter, clean all the intake sensors, throttle body
Are you putting in the cheapest possible gas from sketchy places?
do an idle relearn as well.
Manual transmission and cruise control help alot with gas mileage

Mikeyyy

tell us how you drive please. do you do the PSL? easy on the pedal or floor it? how long are your trips?

guitarsnlikker

FWIW might just be a clogged injector, put some seafoam or techron in the tank see if that helps. I had an acura do the same thing and one tank of techron cleaner cleared it up mileage went up 25%. good luck

steve_333

Thanks for the reply, I've already tried gas tank fuel injector cleaner a couple times and I've sadly had no luck with it.

Thanks for the reply, the car is automatic and does not have cruise control.

It's very rare that I push my car but I sometimes do, I've done tests trying to drive the car as smoothly and fuel efficient as possible and it didn't make a significant difference on my gas mileage when compared to regular/normal everyday driving. I fuel up using well-known companies such as Shell or Petro Canada.

As for the idle, it does seem somewhat low, I'll verify it using an odb connector next time I drive it, what could this be a symptom of?

Thanks for the reply, I'm not quite sure what you mean by PSL. A large majority of the time I am very easy on the gas pedal. I have already tried going a full tank while driving as fuel efficient as possible, it did not make a significant difference in fuel economy sadly. My trips vary by a lot, typically I'll drive in 15-30km intervals with a pretty much 50-50% split between highway and city driving

Colin42

I went from an 05 stick shift with cruise to my new 05 that's auto with no cruise, and I've noticed a decrease in economy, probably a little more than 0.5L/100kms difference. I'm averaging 7.6L/100kms in the new car and I'm driving it easier than the old one.

Low idle could be because the computer doesn't like the data that it sees and isn't sure what to do with it. Is the check engine light on? Clean the throttle body (there's a thread on how do to it somewhere), clean all the intake sensors, check your spark plugs and air filter.

You're supposed to do an idle relearn after you clean intake things anyways so you might as well clean those things and then do the idle relearn. There's threads that mention how to do it here, but off the top of my head:

Disconnect the battery and leave it for at least 20 mins, reconnect the battery and then start the car, make sure nothing electrical is turned on in the car, no lights (parking brake up), no heater fans, no stereo, nothing. Let the car idle for 25-20 mins, the cooling fans should cycle at least twice. And then you should be good to go.

steve_333

I just verified my idle using a cheapie ODB2 connector and I read around 700rpm, which is pretty normal. The cluster gauge was a little inaccurate so that rules that out.

Mikeyyy

PSL = Posted Speed Limit

sdaidoji

iTrader: (1)

what maintenance have you been doing?

air filters, etc.

steve_333

The air filter was changed last year, oil was changed around october, the only maintenance that I can think of that might not have been done for a while would be the spark plugs. The previous owner gave me a pretty comprehensive list of receipts for the car and I didn't see the spark plugs being mentioned anywhere. I had pulled one plug to check its condition a while ago and it seemed like it was in good condition but maybe the remaining three would be different?

mikey1

in my opinion, that doesn't really seem too far off from the norm for a 12-13 year old car,

there are literally hundreds, or even thousands of things that can affect fuel economy....impossible to really pin point it down to one variable,

sdaidoji

iTrader: (1)

go through the list

https://www.civicforums.com/forums/1...e-up-mods.html

also, not sure on the wideband sensors, but when my MPG goes down, usually it's the O2 sensor going bad. but i changed twice at 125 k miles.

steve_333

I'll go through the list, thank you.